Rectifier cooling system



July 24, 1934. s. WIDMER RECTIFIER COOLING SYSTEM I Filed July 21. 1932 Patented July 24, 1934 PATENT OFFICE RECTIFIER oooLING SYSTEM Stefan Widmer, Baden, Switzerland, assignor to Aktiengesellschaft Brown Boveri & Cie., Baden, Switzerland, a joint-stock company 01' Switzer! land Application July 21, 1932, Serial No. 623,797 In Germany July 30, 1931 4 Claims.

' This invention relates to improvements in electric current rectifiers of the metallic vapor arcing type and more particularly to means for maintaining such rectifiers at the most favorable operating temperature.

It is well known that the temperature of an electric current rectifier of the metallic' vapor arcing type must be maintained within a certain range to secure the optimum operation thereof. The temperature of the rectifier cannot be allowed to rise above a certain value otherwise the density of the'metallic vapor would. increase to a point at which back-fires and other disturbances of operation would take place. Such temperature control is best obtained by regulation of the cooling medium such as water supplied to the several portions of the rectifier which are double-walled or are provided with coils through which the cooling medium may flow. The cooling water may be supplied continuously from a suitable source and maybe discharged to waste from the rectifier after serving its purpose. If a sufficient supply of water is unavailable or if the available water is unsatisfactory for continuous supply to the rectifier of fresh water by reason. of impurities which cause corrosion or deposition of sediments, it is necessary that the same water'be'recirculated through therectifier and be recooled in a closed system.

Closed recirculating cooling systems for rectifiers are known in which all' of the portions of the system are connected in series with an external cooler. Only a very slight temperature difference is, however, obtainable between the water inlet and outlet of the rectifier when such recooler is used. The recooler must, therefore, be of'r'elatively large size to obtain sufficient heat transfer from the hot water discharged from the rectifier to the atmosphere particularly when the ambient temperature is high. If the allowable rectifier temperature is only slightly above room temperature, it is not-economical to use the known 'recooling recirculating systems. The use of rectifiers in hot climates particularly where sufficient supplies of fresh water for continuous supply for cooling purposes is impossible to obtain is, therefore, dependent entirely on a satisfactory closed recirculating cooling system.

The greatest voltage drop. andhence the greatest heat losses in a rectifier occur at the anodes and the surrounding are guides adjacent the anodes, both: of which are: heated tovery high temperatures. The heat from such. portions of the rectifier structure must be removed substantial-ly only by radiation to' the: adjacent cooled portions of the structure. The temperature dif ference between the anodes and the adjacent cooled portions of the rectifier is very high so that the water circulated through such portions'may be heated to a relatively high temperature without materially influencing the rate'ofheat flow between the anodes and the cooled portionsof the rectifier. The remaining heat losses of the rectifier, generally conducted through the metallic vapor producing the valve action in the rectifier, are relatively slight and hence the other cooling structural portions must be kept at a relatively low temperature to secure efiicient heat transfer due to the temperature difierenc'e between such vapor and-the cooling portions of'the rectifier in contact therewith.

Itis, therefore, among the objects of the present invention to provide an electric current rectifier of the metallic vapor arcingtype with a closed recirculating cooling system so arranged as to allow the maintenance of the optimum heat transfer from all portions of the rectifier.

Another object of the present invention is to provide an electric current rectifier of the metallic vapor arcing type with a closed recirculating cooling system in which the cooling system is divided into separate circuits cooling =diiferent' portions of the rectifier structure at different rates.

A further object of the present invention-is to provide an electric current; rectifier of: the metallic vapor arcing type with a closed recirculating cooling system in which the cooling system is divided into separate paths in which the recirculatingcooling medium is kept within different temperature ranges.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing which somewhat diagrammatically illustrates one embodiment of the invention in which the portions of the rectifier structure forming paths for the circulation of a cooling mediumtherethrough are divided into separate circuits through which the cooling medium is circulated at different temperatures.

Referring more particularly to the drawing by characters of reference, the reference numeral 1 designates the double-walled bottom of a rectifier, the bottom being substantially in the shape of a frustum of a hollow cone. The aperture through the bottom 1 is closed by a double-walled plate 2 insulated from the bottom as at 3. The

1plate-2and the insulation 3 together form a well to retain a quantity of vaporizable material such as mercury which forms the cathode 4 of thereciii tifier. A double-walled cylindrcal portion 6 extends upwardly from the bottom portion 1 and the open upper end of the cylindrical portion is closed by a double-walled top plate '7 having a cylindrical extension 8 which is also doubles walled and forms a dome in which a portion of the metallic vapor in the chamber formed by the bottom 1, side wall 6 and top plate '7 is condensed.

A plurality of anodes 11 are arranged to ex tend into the rectifying chamber from the exterior thereof through the top plate '7, the anodes being insulated from the top plate by the insulators 12 also extending therethrough. Each of the anodes 11 is partially enclosed by a sleeve or arc guide 13 depending from the insulator 12 to adjacent the bottom 1. arranged within the rectifier chamber and in the area enclosed by the anodes 11 and closely adjacent the arc guides 13. It will be seen from the drawing that the anodesare arranged closely adjacent the side wall 6.

The bottom 1, cathode plate 2, top plate '7, and condensing dome 8 are connected in series by tubing 16; .The dome 8 is connected by tubing 18 with one end of 'a radiator 19, the other end of the radiator being connected with a cooling medium circulating pump 21 driven by any suitable means. The pump is connected with the cathode plate 2 by tubing 22. The tubing 18 and 22 is preferably provided with insulating sections as at 23 and 24 for the purpose of diminishing the degree of electrolytic corrosion when portions of the cooling medium circulating installation are grounded. The use of insulating sections also permits the cooling installation to be kept at ground rather than cathode or tank potential. The above cooling medium circuit provides for the circulation of cooling medium about the oathode 4 and through the portions of the rectifier structure which are particularly in contact with the vaporized materials to be condensed to retain the vapor density within the rectifier below a predetermined amount. I l

The side wall 6 and one end of the cooling coil 14 are connected by tubing'31. The other end of the coil is connected bytubing 33 having an insulating section '34, with one end of a radiator 36,'-the other end of the radiator being connected with a pump 37 for recirculating the cooling medium. The discharge of the pump is connected by tubing 38 having an insulating section 39 with the side wall 6. The above circuit provides a path for the circulation of cooling medium adjacent to and on both sides of the anodes.

Both of the radiators are preferably enclosed in a housing 41 through which air isforced by fan 42 driven by suitable means. The heat. absorbed by the cooling medium flowing through the several circuits is thus transferredto the cur- 'rentof air blown over and through'the radiators and the water is thus recooled. It will be understood that the driving means for the pumps and the fan may be controlled jointly or severally by thermal means associated with the several cooling medium circuits or with the rectifier as is well known; v

In the arrangement shown, radiator 19 of the cathode-condensation dome circuit in whichthe cooling medium should be kept at a lower temperature than in the side wall-cooling coilcircuit, is arranged between radiator 36 and fan 42. The cooling medium in the latter circuit is thus kept at a higher temperature than in the former circuit. The'anodes and arc guides-are A coil of tubing-leis thus kept at a higher and more preferable operating temperature which prevents the condensation of mercury vapor thereon than the other portions of the structure on which it is desirable to condense mercury vapor to control the vapor density in the chamber. The recooling structure may be kept much smaller than was possible heretofore under similar conditions thus reducingthe construction and installation costs thereof and reducing the space required therefor. It will be understood that the radiators may also be arranged in separate recoolers or that the housing 41 and fan 42 may be omitted, it being necessary merely that the cooling medium in the separate paths be kept at different temperatures.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the are that variouschanges and modifications may be made therein without departing from the spirit of the invention or from the scope claims.

It is claimed and desired to secure by Patenti 1. In apparatus of the character described, the combination with a casing forming a'closed re- Letters of the appended ceptacle containing a quantity of 'vaporizable' electrode material and having double walled top, side and bottom portions forming a plurality of chambers for the flow of cooling fluid therethrough, a first cooling system comprising a re-'. cooler, a cooling fluid and means for causing the recirculation thereof serially through said recooler and said chambers formed about said top and bottom portions of said casing, a second cooling system comprising a recooler, a cooling fluid and means for causing'recirculation thereof through thelast said recooler and through said chamber formed about said side wall portion of said casing, and means common to said systems operable to recool said fluid flowing through the second recooler and to simultaneously recool the said fluid flowing through the first said recooler to a lower' temperature whereby the said top' and bottom wall portions of said casing are maintained at a lower temperature than the temperature of the said side wall portion thereof.

2. In apparatus of the character described, the combination of a receptacle having an aperture therein and being provided with a plurality of double walled portions forming separate passages for the flow of cooling fluid therethrough, a second receptacle containing a quantity of vaporizable electrode material closing said aperture and having, a double walled portion forming a passage thereabout for the flow of cooling medium therethrough, a first cooling system comprising a cooling fluid. and means for causing recirculation thereof seriallythrough said passage about the second said receptacle and through certain of said passages about the first said receptacle, a second cooling system comprising a cooling fluid and means for causing recirculation thereof through another of said passages about the first said receptacle, and means common to said systems operable to simultaneously recool said fluids to such difierent temperatures as r to cojointly regulate the rate of vaporization of said material, to affect the direction of flow of vaporized portions thereof and to effect condensation of such said vaporized portions'thereof.

3. In combination with an electric current rectifier comprising a casing forming a closed receptacle having bottom, side and top wall portions material, of chambers formed about the respective said wall portions providing separate passages for the flow of cooling fluid therethrough, a cooling coil supported within said receptacle intermediate the top and bottom portions thereof, a first cooling system comprising a cooling fluid and means for causing recirculation thereof serially through the said chambers formed about the said bottom and top portions of said casing, a second cooling system comprising a cooling fluid and means for causing the recirculation thereof serially through the said chambers arranged about said side wall portion of said casing and through said coil, and means common to said systems operable to simultaneously recool said fluids to such different temperatures as to cojointly regulate the rate of vaporization of said material, to affect the direction of flow of vaporized portions thereof and to eifect condensation of such said vaporized portions thereof.

4. In combination with an electric current rectifier comprising a casing forming a closed receptacle containing a quantity of vaporizable cathode material and having bottom, side and top wall portions, a coil supported within said receptacle intermediate said wall portions thereof and forming a passage for flow of cooling fluid therethrough, and a plurality of anodes depending into said receptacle intermediate said side wall portion and said coil, of chambers formed about the respective said wall portions providing separate passages for flow of cooling fluid therethrough, a first cooling system comprising a cooling fluid and means for causing recirculation thereof serially through said chambers about said bottom and top wall portions, a second cooling system comprising a cooling fluid and. means for causing recirculation thereof serially through said chamber about said side wall portion and. through said coil, and means common to said system operable to simultaneously recool said fluids to such different temperatures as to cojointly cause flow of vaporized portions of said material in direction away from said anodes and to effect condensation thereof.

STEFAN WIDMER. 

